This invention relates generally to guardrail systems extending along a roadway, such as a conventional highway or a race track, for redirecting an errant vehicle back onto the roadway. It is especially directed to a novel, impact attenuating compressible barrier wall system capable of redirecting an errant vehicle back onto the roadway with minimal decelerating effect, minimal damage to the vehicle, and reduced risk of injury to the driver.
Roadways are often lined with protective barriers such as concrete walls and/or fixed guardrails including standard metal W-beams. When a car strikes against a concrete wall or an unyielding guardrail, even at a shallow angle the car can experience significant deceleration and damage and the driver can be seriously injured.
One prior effort to deal with these problems has been the placement of bundles of tires tied together and stacked in front of fixed obstacles such as the concrete barriers and unyielding guardrails. However, when hit at a shallow angle at high speeds, the tire walls can snag the car and violently reject it back into the stream of traffic, creating a dangerous situation for all drivers.
Another proposed places longitudinally extending vehicle interfacing rails adjacent the roadway and resilient energy absorbing cylinders between the rails and the fixed obstacles. Upon impact, the rails move with the car, absorbing energy and reducing damage to the car. This proposal works very well, preventing snagging and, after impact, restoring the rails substantially to their original operative position.
The invention described herein is considered to be an improvement over this latter proposal in that it eliminates the interfacing rails and relies only on a novel arrangement of resilient energy absorbing cylinders to absorb the energy of an impacting errant vehicle and to redirect the vehicle back onto the roadway.
Accordingly, the primary object of this invention is to provide an impact attenuating barrier wall extending along a roadway, the wall including a novel arrangement of resilient energy absorbing cylinders which, upon impact by an errant car, effectively intercept and redirect the car back onto the roadway with minimal damage to the car and reduced risk of injury to the driver.
The novel barrier wall of the invention achieves its objectives by providing a plurality of large diameter, compressible, resilient energy absorbing cylinders positioned in side-by-side relationship along the roadway between the roadway and an outer fixed protective barrier or obstacle such as a longitudinally extending concrete wall on a standard fixed guardrail. Gaps are formed between the inner halves of the side-by-side cylinders adjacent the roadway, and smaller diameter cylinders are placed in those gaps to substantially fill those gaps. Upon initial impact by an errant vehicle, the inner halves of the larger and smaller cylinders are compressed to form a substantially continuous vertical surface intercepting the vehicle, absorbing the energy of the vehicle and reducing damage to the vehicle. Placing the smaller cylinders in the gaps prevents snagging, and the cylinders effectively redirect the vehicle back into the roadway.
The cylinders are preferably constructed of a high molecular weight/high density (HMW/HD) polyethylene material of the type disclosed in U.S. Pat. No. 5,403,112, and possess the unique ability to first dissipate large amounts of energy upon impact by a vehicle, and then restore themselves to about 90 percent of their original shape, thereby substantially maintaining the integrity of the barrier wall through repeated impacts.
Other objects and advantages will become apparent from reading the following detailed description of the invention wherein reference is made to the accompanying drawings.